This invention pertains generally to test equipment and particularly to equipment to indicate the readiness of a rocket motor to be fired.
It has been standard practice for some number of years to provide "certified" rounds of the HAWK missile (a standard ground-to-air defense missile of the United States Army and many allies). A certified round is a missile which, because of the methods used in manufacturing each missile and the protection provided for the working parts of the missile, is guaranteed to operate properly in the field.
Unfortunately, however, there is no practical way in which the solid fuel in a rocket motor such as is used in the HAWK missile may be protected against the deleterious effect of changes in ambient temperature over a period of years. In particular, when a certified round is emplaced in an area where it is subjected over a period of years to ambient temperatures, such as are ordinary in a tropical or semitropical country, the solid fuel in the rocket motor becomes unstable and may not be burned in the desired manner. In order to maintain the status of each HAWK missile as a certified round, it is, therefore, necessary periodically to change the solid fuel in the rocket motor. Obviously, such a change should be scheduled only after the solid fuel in the rocket motor has been subjected to elevated temperatures for a sufficient period of time to cause a significant change in the characteristics of such fuel.
It has been proposed that a record be kept of the temperature and duration of time at any elevated temperature to which each HAWK missile is subjected in the field and then, with such a record, determining whether or not the characteristics of the solid fuel have deteriorated to any significant degree. It is evident, however, that such an approach to the scheduling of periodic maintenance entails some risk in that the records for each HAWK missile must be separately maintained over a long period of time as the location of the missile is changed to meet different tactical situations.